First Impressions: Metabones Speed Booster

The Metabones Speed Booster is shown here mounted on a Sony NEX-6 with a Canon EF 40mm F2.8 lens.

We've had the Metabones Speed Booster in the office for a few days and wanted to share some initial thoughts on the possibilities and challenges presented by such a unique product. While Metabones has announced plans to support a variety of lens/mount combinations, its first offering is a Canon EF to Sony NEX Speed Booster, so we put some Canon full frame lenses on our Sony NEX-6 and did some comparisons alongside the Canon EOS 6D we're currently reviewing.

What is the Speed Booster?

As we reported recently, the Speed Booster is an adapter that allows for a full frame lens to be mounted on APS-C or Micro Four Thirds mirrorless cameras. There are two reasons why this is very big news, and both revolve around the optics inside the adapter. Firstly, Metabones claims that by reducing the image magnification, the Speed Booster gives an overall focal length multiplier of around 1.09x, promising a nearly full frame field of view on APS-C. The second claim, as its name implies, is that the Speed Booster increases the lens's speed by a stop, turning an F2.8 full frame lens into an F2.0 optic that allows for low light shooting at a lower ISO sensitivity.

This image was shot with the full frame Canon EOS 6D using the EF 35mm F1.4 L lens. The green crop illustrates the field of view when shot from the same position with an APS-C Sony NEX-6 using the same 35/1.4 lens via the Metabones Speed Booster. The blue crop shows the native field of view of the NEX-6 if shot from the same position at the same focal length without the Speed Booster adapter attached.

How can an adapter change the focal length and aperture of a lens?

The Speed Booster is most easily understood as being the opposite of a teleconverter – in that it reduces your focal length. This, then, has a domino effect on the F-number of the lens. Because the F-number is the focal length divided by the width of the entrance pupil, reducing the focal length without changing the entrance pupil increases the F-number. So, adding the speed booster to a 50mm F1.4 lens turns it into a 35.5mm F1.0. But, since we’re then going to mount it on an APS-C camera, we have to multiply these numbers by the camera's 'crop factor' if we want to compare this lens-plus-adapter combination to a full frame camera. The end result is a 53.25mm equivalent lens that gives the same depth-of-field as an F1.5 lens would on a full frame camera.

The Metabones Speed Booster contains optics, designed by highly regarded lens designer Brian Caldwell, that match the image circle of a full frame lens to a smaller format sensor.

And, if making lenses faster sounds like witchcraft, don’t forget that when you normally mount a full-frame lens on an APS-C camera, it illuminates an area larger than the sensor. With the Speed Booster, rather than losing this light, you’re effectively condensing it all onto your sensor. Again, it's doing the exact opposite of what a teleconverter - which loses light - does. The end result is that in terms of light capture and depth-of-field - as well as field of view - your full-frame lens behaves essentially as it would on a full-frame body.

AF compatibility

The Canon EF to Sony NEX version of the Speed Booster supports autofocus. But before you get your hopes up, here's a quote from Metabones' own product page:

'Autofocus speed is very slow and inadequate for most moving subjects. The autofocus speed is unfit for professional use for sure, and it would disappoint most enthusiasts.'

Our experience confirms this. Essentially you need to think of the Speed Booster as a manual-focus adapter. Even in good light, you'll get much faster results by focusing manually, particularly on a camera like the Sony NEX-6, which offers focus peaking. This is not surprising if you think about it, as the adapter is mating a lens optimized for phase-detection autofocus (PDAF) to a camera that uses a contrast-detection autofocus (CDAF) system.

It's also worth noting that the Canon EF to Sony NEX mount model is currently the only Speed Booster version to support AF at all. And the choice of AF-compatible lenses is limited to Canon EF models introduced in 2006 or later. Older (and third party) lenses operate in manual focus only.

Optical performance

As you can see from the examples below, Metabones' claim of 'almost full-frame coverage' is no idle boast. We've shot our resolution chart using the same lens on both the NEX-6 with Speed Booster adapter, and the EOS 6D; each camera was shot with its sensor plane located the same distance from the resolution chart. Based on our image comparisons, we calculated a focal length multiplier of about 1.07x, which is virtually identical to the company's assertions.

The Speed Booster combines with the Sony NEX-6 to provide a slightly narrower field of view compared to the full-frame Canon EOS 6D. The raw files were processed in ACR 7.3 beta to match white balance and brightness, with all other settings, including sharpening at their defaults.

As the 100% crops below attest, the center sharpness performance of the Speed Booster is very impressive. You'd be hard-pressed to find significant difference between the two files in the center of the image, other than the slightly higher resolution of the 20MP Canon EOS 6D versus the 16MP NEX-6. In the second set of crops, however, taken from the lower left corner of the chart, you can see softer corner performance and more prominent chromatic aberration (CA) from the Speed Booster.

Sony NEX-6 + Canon EF 50mm F1.4 USM with Speed Booster. 100% crop

Canon EOS 6D + EF 50mm F1.4 USM. 100% crop

100% crop

100% crop

With such impressive results, we thought it would be interesting to see how optical performance fares at a very wide aperture. The image below was shot with the same Canon EF 50mm F1.4 USM lens on the Sony NEX-6, and the Canon EOS 6D, but this time at an aperture of F1.4. Raw files were again, processed with ACR 7.3 beta.

In the image above, you can see more obvious lens distortion at F1.4, as you'd expect. (Click the image for a full resolution version.) In the 100% crops below you can see that image quality suffers somewhat in the corner of the frame compared to the full frame EOS 6D.

We've also found that the Speed Booster introduces significantly more vignetting in image corners with the Canon EF 85mm F1.8 lens than you find on the full frame Canon EOS 6D, presumably due to a mismatch between the size of the lens's rear element and the Speed Booster’s front element.

Sony NEX-6 + Canon EF 85mm F1.8 USM with Speed Booster: F8, ISO 100

Canon EOS 6D + EF 85mm F1.8 USM: F8, ISO 100

Still, you can't help but be impressed with the sharpness performance of the Speed Booster at an optimum aperture. And while vignetting, CA and large aperture corner performance are concerns, we must stress that 100% crops of test charts can overstate the practical implications of how the lens performs out in the real world. So we took the Speed Booster out of the testing studio for some shooting.

Real-world usage

There's no denying the pleasure of putting your SLR lens on a mirrorless body without significantly limiting your field of view, particularly with wide angle primes. And the ability of the Speed Booster to allow more light to reach the sensor should mean that you can capture equivalent exposures while shooting at an ISO setting that is one stop lower than using the same lens without the adapter.

In the low-light scenarios above, using the Speed Booster allows the Canon EF 40mm F2.8 STM lens to behave as an F2.0 optic, thus letting you shoot handheld at ISO 3200 and ISO 1000, respectively.

We did find, however, that shooting at the widest possible aperture (so F1.0 on a nominal F1.4 lens, for example) consistently resulted in a darker exposure. We found this to be true whether we allowed the Sony NEX-6 to meter the scene or set exposure manually. As you can see in the comparison below, maintaining an equivalent exposure between F1.4 and F1.0 actually results in a darker scene.

The most likely explanation is not due to any flaw of the Speed Booster. Rather, with the phenomena known as pixel vignetting, in which at very wide apertures, the light gathering ability of the sensor's photosites diminishes slightly. If you've never heard of this, it's because characteristics like these are often corrected automatically in-camera based on the information the camera has about the lens mounted on it. And of course, this chain of information is affected with the use of the adapter. We want to stress, however, that on all of the EF lenses we've used with the Speed Booster it is only at the maximum aperture (enabled by the Speed Booster) that we've seen this occur.

Summary

There's a lot to be excited about with a product that so transforms lens behavior and addresses such a long-standing issue for photographers who long for the wide-angle and light-gathering performance of their older full frame lenses on their newer APS-C body. Image quality is very impressive, with results that compare exceptionally well against a full frame sensor. You do pay a small price in terms of corner softness and CA.

The biggest remaining challenge, however, with the Canon EF to Sony NEX mount is AF speed, a direct consequence of pairing a PDAF-optimized lens on a CDAF sensor. And to their credit, Metabones makes it very clear that AF performance is going to lag far behind what you'd get by using the Sony NEX's conventional AF system.

This does effectively make the Speed Booster an even more niche product, as it's best suited for manual-focus shooters. We'd be keen to see a camera manufacturer license this now-proven technology and offer this optical quality and near-full-frame performance mated with an effective AF system. But for now, we tip our hats to Metabones for releasing a product that accomplishes what many had thought nearly impossible.

Comments

Because the F-number is the entrance pupil divided by focal length, reducing the focal length without changing the entrance pupil increases the F-number.I think, it's wrong here.When reduce the focal length without changing the entrance pupil will DECREASE the F-number. So it's from 50mm f/1.4 will be 35mm f/1.0.

No, the F-number increases. If you reduce the denominator in a division, while keeping the numerator constant, the quotient becomes larger.Therefore, changing from F/1.4 to F/1.0 really is an increase. There is a good reason why you should write F/1.4 and not F1.4, like many people unfortunately do.

A nice product for people who want an FS100 videocam to mimic a FF camera. The small optical distortions will not offset the advantages, particularly for video. $600 is a lower price than to wait for a video-optimized FF DSLR that may never appear or cost >$25k, or settle for a VG900 with awkward controls and an irrational mount system that forces one to pick cropping and vignetting or lose AF.

The problem will be that, without careful manual focus, the slower AF and narrow DOF will cause havoc. Might this challenge be steeper still in the m4/3 version?

The full frame mirrorless VG900 is the swiss army knife of cameras since it will work with almost all full frame and APS-C lenses. It has both full frame and APS-C modes, the best OLED EVF, zoom rocker button for power zoom E mount lenses and shoots 24.3 full frame jpeg/RAW stills with shutter speeds from 30-1/8000 sec. Try using full frame Pentax K-mount lenses on a full frame DSLR without chopping off the aperture control on the mount.http://farm9.staticflickr.com/8489/8159590765_803d943a74_k.jpg

These devices have been around in astronomy for many years, and are called focal reducers. They operate by artificially reducing the apparent focal length by the use of several optical elements and usually offer significant reductions (x0.63, x0.33 are typical) in 'speed' of the telescope, so that, for example, a standard Schmidt-Cassegrain telescope built, to F/10 would become an F/6.3 telescope, whilst also increasing the field of view. They can be very useful but they do insert extra glass components into the light path and this inevitably affects image quality, including CA, reduced contrast and image distortion. I am surprised that they have taken so long to appear in the digital camera market. After my experience with using focal reducers I would hesitate from buying one for photography. They are great devices and do the job they are designed for, but I find that after a while, the negatives start to bug me.

Indeed they've been around for a long time with telescopes, but in the photography world they'd never work before the advent of mirrorless cameras since you never had the space to put them between the lens' and body (without drastically changing your max focus distance). Also, I believe Kodak had a patent on such devices, which may just be lapsing now...

Wrong... because even if there was an AF motor (which Canon doesn't use btw), the camera body (NEX) still only uses contrast detect, and the lens' motors/gears are setup for a phase detect type movement, not short rapid micro-movements that contrast detect needs to operate.

I actually have been looking at producing a glassless autofocus adapter for manual lenses on E-mount, initially as a university research project and then as a product. Getting interface design constraints to enable fast AF is critical to this. Let's just say that Sony thus far has not been very helpful. :-(

Well, for one, I own full frame and nex bodies. I just spent $830 on a 35/0.95, which is basically equivalent to the $150 50/1.4 I already had for full frame. My 2.8 zooms would go from slightly awkward on nex to every bit as usable as on full frame. And I'd have the option to use my 600/4 at an actual 600mm focal length with nex if I so choose.

Yeah..ryanshollI get what you are saying (quite comically I might ad, LOL!)..I have a 5DIII and two MFT cameras..but the last thing I want to do is put one of my giant L lenses (even bigger with the adapter) on my MFT camera, with slow, manual, no or whatever focus...I personally would just rather have the small, fast AF lens that make my MFT so awesome...and SMALL and FAST. To me it is kind of like a flea %#@*&%+ an elephant.... to marry L glass with a GX1 ....LOL....but I get it..everybody has a different outlook...its all good! ...put your right foot in....

I'm hoping the MFT version uses different optics to this adapter, so that the focal length is retained on the smaller MFT sensor - i.e. a FF 50mm provides more or less the same angle of view on an MFT camera. Given the different aspect ratios (3:2 versus 4:3) I guess in practice this would actually mean an equivalent vertical focal length and some cropping to the horizontal focal length, but I'm not sure.

IMO the biggest advantage of this adaptor isn't the increased light gathering (although that's very nice), it's the retained shallow depth of field. There's some really nice older fast lenses out there (Nikon 50mm f1.2 AIS, Nikon 105mm f2.5 AIS, etc.) that are, for their performance, quite light and small, and very affordable.

I suspect though that the demands on the optics to shrink the image to such a degree might significantly increase the corner falloff and CA evident in the APS-C version, to an extent where it can be seen in real world images.

It does use a different optical formula, but it doesn't give you a greater multiplication factor, apparently there are limits in terms of how far the lens' can protrude into the body cavity and the size of the optics as well. So they have a slightly modified optical formula for m43, but more for IQ related reasons that brightness/width.

The NEX-6 kit with the terrific Canon 40 2.8 looks great. And I wonder how many who are complaining about "optical defects" like CAs or contrast, noticed any of these things in the real world images below.

A 28 f2 Pancake lens with excellent IQ for $200 on a svelte body the the NEX-6/5N sounds great (the Zeiss 24 f/1.8 is $1100) to me but I usually don't shoot test charts. And if I did, I'd be willing to live with a few minor optical flaws.

In my humble opinion, people will always get upper/lower case wrong, so it will only create an even more confusing system.

Focal length and maximum aperture are physical quantities depending only on the lens. Depth of field depends only on magnification, aperture and circle of confusion. None of these care about the size of the sensor sitting behind.

So, 35/1.4+SB indeed becomes a 25/1.0, physically, but I propose we say it "shoots like" a 37/1.5 on full-frame in terms of FoV and DoF. We could also have said "35mm equivalent" focal length and DoF just like the way we discuss APS-C and digital compact cameras.

You can't ignore the disadvantages this adapter comes along with (more CA, lower contrast, corner softening, poor AF, more weight and bulkiness of FF lens/adapter). That's why it won't be a tool for any photographer in the mirrorless sector. But for some the adapter might prove useful, especially if it comes to wide angle or high aperture FF lenses you possess anyway.

Question: What about the adapter combined with a wide angle shift lens? Will shiftening be increasing optical flaws?

Not really "more CA", "lower contrast", etc. because the adapter and an f1.4 lens really isn't any worse than a purpose-built f1.0 lens for APS C.

Ad far as "more weight and bulkiness", you're still talking a lot smaller and lighter than a FF DSLR running those lenses without an adapter. A Leica M 240 would probably beat it, and the Leica lenses are surprisingly compact. But the M doesn't have "poor AF", it has no AF at all. And an M and a nice 3 lens kit will set you back 10-12 large.

Now, if you pitted it against a FF mirrorless running those f1.4 lenses without the adapter, the FF would win. But those don't exist yet.

One of the reviewers tested a shift lens, and was surprisingly pleased. Personally, I'll believe that when I see it.

You make some bold claims, maybe it won't become a tool for you personally, everyone has their likes and dislikes, but I have a large number of Canon mount lenses I will be looking forward to testing. On M4/3. Minor CA and contrast tweaks are easily made in post. CA is for most purposes gone in B/W conversions as well. Landscape photography is an area where manual focus isn't much of a problem, and I'll have a lot of fun just testing out the new creative possibilities. Real world photos are much different than resolution charts, don't get me wrong, resolution charts are useful for comparisons, but they're not the final word on a lens' usefulness. Maybe LensRentals will stock them, and you can try one yourself without a big $ investment. It might open your eyes, or it might confirm your opinion. I say look at it with an open mind. More possibilities are always better than less when it comes to the glass, don't you think?

Also consider that lens' makers (Canon/Nikon) well (should) re-release their lens' to better behave with contrast detect auto-focus, since both seem to be pushing live view as well as video applications. If they do re-release their FF lens' with such modifications, then AF performance in theory should improve with contrast detect mirrorless cameras using an adapter such as these.

It may not be a big deal for the Mirrorless only shooters, who may most likely don't care for the big SLR lenses anyway, but it definitely is a very nice product for the Canon FF owners that also own a NEX system, like myself, I am shooting Canon and Nikon for the last 20 years and also own a NEX7, already own the previous generation Metabones auto focus EF to NEX adapter and their Nikon F to E adapter for my Nikon AIS and D lesnes, works great for me, (other than the 1.5X crop facor limitation), being able to mount all my Zeiss ZE/ZF2, Nikon, Canon EF lenses to the NEX is just so cool, even I am willing to spend the money on a new set of E-mount lenses, there is no TSE 17, TSE 24, 851.2, 200F2 and 300 2.8L available for the NEX system today, and with the little adapter, all my lenses are useable on any NEX.

Alphaloki: I agree with you basically, although I don't think there will be an SB for my Carl Zeiss lenses from the film era.And: I had a teleconverter but didn't like it because of its flaws in back light. Not any device can fulfill your expectations.

Dan_168:That's what I mean! This SB is not made for any mirrorless shooter (who likes AF, e.g.) but for people like you having FF lenses already. And you should be aware of the risk of optical flaws. Adapting a FF lens at a mirrorless camera comes along with a crop factor of 1.5, which might be an advantage or a disadvantage. But there's no affecting IQ. This new adapter is different! Its glass elements affect IQ more or less, depending on each lens/adapter-combination. You will have to find out which lens of yours the SB works well with!

why you need to have it in a mirrorless in a first place?yes, to put fast prime and get proper field of view and geometrical aperturee.g. even cheapest FF 50\1.8 will become a fast nice wide angle primewhy do you need fast apertures? to shop people with small DOFshould I care about "a bit softer corners" ? hell no!

very nice device then =)

looking forward for mainstream lens makers to support this initiative!

sigma, tamron, tokina - wake up!!!

p.s. I don't think that Nikon\Canon will support this as they have their own marketing strategy to separate FF and cropped lenses....

The biggest market for this device is video shooters (the EOSHD crowd are going nuts over it). For them, the slow AF is not an issue since they mostly manual focus anyway, and putting a big lens on a tiny camera is no issue for them either, since they use tripods and rigs (the adapter has its own tripod mount for just this reason).

One thing not mentioned in the article at all is that the adapter gives you aperture control from the mirrorless camera body, since the EOS system is all electronic aperture control, the cheapy manual focus lens adapters that are out there for NEX and m43 can only use EOS lenses wide open. So thats aperture control, an angle of view closer to the original, and a stop brighter. Just those 3 advantages alone will be enough for this to sell well.

The m43 version will be an even bigger hit - the GH2/GH3 video community cannot wait to get their hands on this thing.

Agreed. Have a look at NoFilmSchool to see all the excitement about it, and to check out some excellent videos made with this adapter. Video professionals using the BMCC, FS100. et al are already salivating at the prospect of using the Speed Booster.

The calculation in the article is wrong... the crop factor affects the focal point only (35 x 1.5 = 53.3) but the lens speed of the adapter + lens combo will stay the same at 1.0, not 1.5! When you mount a FF lens on an APS-C camera the lens speed does not change!

Then lens "speed" (in terms of light-gathering power) indeed does change with this adaptor, as it is focusing more light on a smaller area (thus increasing the amount of light reaching the sensor, by up to a stop). That's the ingenuity of the device—and I'm surprised it took this long for someone to figure out :)

So you pay a bucketload of money in order to mount (comparatively) huge lenses on small bodies, you lose resolution and AF performance, but get higher levels of chromatic aberration... makes sense.Wouldn't it be simpler - and less ruinous - to use your Canon FF body when you want to use EF lenses?Just saying. Some may think otherwise and that's OK with me. It's their money anyway.

Well, bobbarber, I was assuming anyone who has EF lenses would have full-frame bodies to mount them on... apparently I was wrong.As I said, it's your money. And I have no right to tell you how to spend it.

You don't need in fact a FF body to compare. Your GH2 has a crop factor of 2, the metabones has 0.71, so your combined crop factor is 1.42.Since canon APS-C cameras have a crop factor of 1.6, something like the 60D will compare to your GH2 + metabones.Of course, I'm noly comparing the crop factors, there are lots of differences between those two cameras...

Yes, I'm being sporting a little bit, and no, I don't own any Canon EF lenses. I do have Minolta MD and Nikon film lenses that I would like to use with a similar adapter on m43. My 50mm 1.4 would be 100mm 1.4 without adapter, and 50mm 1.0 with. That's useful to me! Enjoy whatever equipment you use.

I have Canon FF lenses that I used on older 300/350 Canon bodies...After years the lenses are fine but bodies are behind the camera I use now: Olympus OM-D. Some WA and fast lenses are interesting!. These lenses on MFT cameras would actually make sense if image quality is good. Listening to reports of whom has been trying them say results are great. They are a niche product for people like me that have some expensive optics that could get some use, or video people, or for those older but special lenses that combined in newer MFT or NEX mounts would still shine. I am interested in samples for MFT mount given smaller sensor and probably even better quality of the image resulting from the Metabone lenses. Why so many people shoot these adapters down without even having any experience on their image results is a mystery to me. Just because it does not apply to their personal camera/lens/shooting universe is certainly not a reason to be so negative or disruptive!! ... or sarcastic :((

Thank you, bobbarber. I do enjoy my equipment a lot, especially when I use my two OM prime lenses on the E-P1, mounted via Olympus MF-2 adapter (which has no hocus-pocus properties). My OM lenses never complained not to be used as full-frame lenses, and neither did I. In fact I bought them to give me the equivalent focal lengths I wanted: 28mm->56mm, 50mm->100mm. (The 50mm is f/1.4, an aperture value I seldom use because it gives me flat, overexposed images and washed-out colours.) I use my equipment for photographing, instead of using photographing to justify my purchases, as some people do (I'm not implying that's your case). I try to make the most of it, but I never forget the equipment is ancillary to my photography.

amazing how many people JUDGE and write without any sense or knowledge (!) ...I guess this is a human trait... It would rather make more sense to wait for some more real tests done from real people and ....in terms of it applicability: different strokes for different folks... :))

The problem I see here is CA, not resolution. Yes, the resolution is inferior on APS-C (we all knew it would be, right? RIGHT? ;) ), but still is more than enough for the vast, vast majority of users.

But correcting CA, ugh. I always read phrases like "easily corrected with software". I'm pretty good with software, but all of my easy corrections of CA seem to wash color out of parts of the image I don't want, or miss part of the CA, or whatever.

Still, a good product. I would buy one for m43. Since I have legacy lenses from two makers (Minolta MD, Nikon), I would be most interested in a general adapter for the mount.

When one sees the detailed lab shots, there is a substantial decrease in critical quality areas. And their first claim is - it should improve the quality. This is false. If this were a somewhat $60 adapter, so what. But for their price it is targeted to take the money from innocent consumers.

Better buy a decent matching new lens instead, and get out - take pictures in life not the lab.

Unit price of about $ 60-80. This is indicated by pictures shown here.The excess of the price to 10 times is fraud.I can not understand those who are seriously discussing is not an invention and a breakthrough in the crucial field of optics. Perhaps people like to listen tobeautiful tale. As well as believing in them.

@ThomasSwitzerland - You have to keep in mind that this DPR review is an apples to oranges comparison - not a criticism of the review itself, which is clear, detailed, informative and well-written, but it is apples-to-oranges from the ground up.

The press release claims "...increases MTF and has a focal length multiplier of 0.71x. For example, the Canon EF 85mm f/1.2L II lens becomes a 59mm f/0.9 lens on a Sony NEX camera, with increased sharpness." All these claims are indeed true when the comparison is done on the same camera body! (NEX-6 vs NEX-6)

This DPR article shows that a EOS 6D has better IQ than NEX-6 even when SB is used. That is not a drop - IQ still increased - just not enough for NEX-6 to defeat EOS 6D. That's all.

The aperture is normally placed at an optimal spot in the lens design. This changes with the adapter adding lens elements at the back. Is there any effect visible of that less optimal adapter spot? With different stop settings, along the focusing range? The vignetting observed could already be related to this shift.

The last bit of this article is incorrect. f/1.0 is not a full stop faster than f/1.4, so the last two shots did not have identical exposure. As you reach f/0 (which is about where many microscopes operate), the light does not go to infinity. f/1.4 is about the last stop where dividing by 1.414 to go up a stop is a fair approximation (this relies on small angle approximations such as sin(x) being approximately equal to x).

For a more detailed explanation, see: http://en.wikipedia.org/wiki/Numerical_aperture#Numerical_aperture_versus_f-number

NA sets exposure. f-stop and m-stop are derived from NA. As a sidenote, I'd love to see dpreview operate on m-stop and mISO.

Look at the Wikipedia article titled f-number. It is a ratio between the lens focal length to the diameter of the entrance pupil. It is an approximation not an exact number just like the focal length of the lens is an f1 is about a stop faster. And seeing as it is a ratio which is division, I fail to see how it could be zero. If I am not mistaken, zero is impossible in division or at least I was told back in school, and plus my calculator also seems to think so. Now you can approach it that is true, but the number gets smaller and smaller, never arriving at zero.

If the lens were flat and not in contact with the object, you would be correct. In the case of microscopy, the object can be immersed in the optics (e.g. oil immersion microscopy) or otherwise surrounded by optics from all directions. You're not quite at f/0, but close enough it doesn't matter anymore (performance is nearly identical to f/0).

"The end result is a 53.25mm equivalent lens that gives the same depth-of-field as an F1.5 lens would on a full frame camera."

How would the crop factor influence the depth-of-field? To my understanding, the crop factor should have no influence on the effective DoF from the lens, so you would end up with the angle of view from a 53.25mm equivalent, but the DoF of the (effective) f/1.0 aperture.

If it were otherwise, we would see a lot more bokeh in compact shots, right? Please enlighten me ☺

It doesn't, *but* if you want to exactly recreate a scene with the same field of view and depth of field on different sensor crops then you get equivalents, such as 35mm f1.8 on APS being equivalent to 52.5mm f3.5 on FF, which is what DPR is talking about.

Basically the 50mm f1.4 on the Metabones adapter would *look* like a 53.25mm f1.5 lens on an FF camera.

DoF is relative to *magnification*. Consider that if you were to take a picture from a 35mm "full frame" sensor and then take a 1.6x crop from the same sensor and enlarge both to the same size, that the 35mm crop would be less magnified than the APS-C crop. You can do this digitally. The more dramatic way to observe this is to look at a small 3x5" sized thumbnail from a distance and then look at a 100% crop close up. From far away and smaller, much more of the scene will appear to be in critical focus. From a 100% crop, much less will appear in critical focus.

Part of the magnification here is the focal length of the lens. If you shoot a scene from a fixed location with a 300mm lens and a 35mm lens, aiming at the same object, same distance, same aperture, etc, then the image from the 300mm lens will have much shallower DoF. Note however, that if you cropped and enlarged the same portion from the 35mm lens that you'd recover the same DoF (when viewed at the same size/distance).

Due to rendering the AF useless it's definitely a niche product. Anyway, it looks attention-grabbing since for the enthusiast photographer (not the pixel peeper) it delivers some attracting features enhancing the possibilities of the camera.Well done.

Except that at widest aperture the resulting image becomes darker. Read the preview. What is the point of taking a f/1.4 lens to f/1.0 if its darker? Plus chromabs are increased and contrast is lost. Not to mention it makes the lens softer on the corners, and introduces vignetting.For the price of this adapter, you can get a second hand original 5d body and not have to worry about compromising image quality. Since that's what we all care about.Right?

A) Are you implying that the DPReview test is innacuate?B) Find me another review/preview with test charts and not ambient light testing.I am willing to admit that the wide aperture test above with the red pipes is open to inconsistency as it seems to be shot outdoors.Otherwise it's easy to see that there are major optical drawbacks to using this. You would have to be delusional to think otherwise.

Try to find a 24mm f1.4 (FF equiv) lens for an APS-C body !!!You get some FF features on an APS-C body. Therefore you have to take some compromises. So it's simply a matter of what counts the most for your style of photography. Life is always a trade off.

If you look at the shutterspeed used, it's twice as fast for the F/1.0 setting. So it's "darker" for expecting it to be equalized by the faster shutterspeed. To really see if you're getting an increase at F/1.0 dpreview should have taken another exposure at the same shutterspeed as the f/1.4 to see any differences.

Basically it's still "brighter" than if you only had f/1.4 as an option, but not as bright as a theoretical f/1.0 lens', though if you do some research you will find the actual "T-stop" on hyper primes actually drops off as well at extreme apertures. So this was pretty much expected

I find it interesting naysaying 400% pixel peepers demanding perfection from a revolutionary introduction 1st generation new technology (to consumer cameras) adapter that does so much at only $600. dont buy it if you are so righteously offended that smaller sensors can use FF lenses and get similar results and then some. What a bunch of wet blanket elitists. Go have fun with your gear and applaud new technology and the people who have the courage and brains to create something worth while. Geez! if there was no innovation you would all still be using peep hole cameras! you lot must be quite the life of the party. What have you created? My hats off to the men behind this. I cant wait to use one. Some valid points about some issues but you dont have to use one. Manual focus primes on this and vor video will be a boon. This will only get better. Where was digital photography 10 years ago? look at it today!

Its not constructive criticism I have issue with. Some people are just FF snobs and 400% pixel peepers. This is a great new tool for APS and M4/3 people. The FF snobs hate it that you can use "Their" precious lenses and get similar or better results.

First of all Trollshavethebestcandy, this is not a revolutionary product and is certainly not based on new technology (your consumer camera addition means nothing).Secondly people used to get blasted for being 100% pixel peepers, and now when dpreview post 100% samples you call them 400% peepers. It's plain to see, even in the 100% crops that this adaptor has several image quality shortcomings.Thirdly, the original press release stated there would not be a drop in image quality, but there is, so if you want to sweep their inaccurate claims under the rug and purchase this $600 product that makes good lenses bad, then its your money to throw away.Calling out full fame users like they are angry children while ignoring the plain visual facts in front of you is just immature on your part. If one wants to be a purist and use a lens of a camera that it was designed for, let them. Just as if you want to fork out good money for this adaptor and get some sort of imaginary benefit, go for it.

The press release claims "...increases MTF and has a focal length multiplier of 0.71x. For example, the Canon EF 85mm f/1.2L II lens becomes a 59mm f/0.9 lens on a Sony NEX camera, with increased sharpness." All these claims are indeed true when the comparison is done on the same camera body! (NEX-6 vs NEX-6)

This DPR article shows that a EOS 6D has better IQ than NEX-6 even when SB is used. That is not a drop - IQ still increased - just not enough for NEX-6 to defeat EOS 6D. That's all.

Anyway, there has never been a general purpose focal reducer for a professional camera either. The concept of focal reducer has been around for a hundred years but a general purpose one applicable to large aperture lenses and wide angles had not been available until now - you can't just transplant one made for telescopes and make one. It is this part which is revolutionary.

There's so many naysayers here, unbelievable. The great photographers of our time never were so worried about the sharpness of their corners - they were too busy taking great photographs with whatever equipment they had available. More posters here should take notice of that.

@Fmian - you seem to be forgetting thst the current crop of nex sensors get results like that from every lens fitted to them. Looking at these test results is meaningless unless you can see the same test chart shot without the adapter with a known lens - i.e a lens you know the corner characteristics of. Then we could see if that loss of resolution and CA is the sensor or the adapter. My bet is on the sensor, because as an NEX user, I see that kind of resolution loss and CA in the corner of every shot I take with every lens and every adapter. Luckily for me, my clients don't study my prints through a loupe!!!

Effemianate...I think you have a lose grasp on how awesome this is albeit not the second coming of HBC. What product is revolutionary and ALMOST perfect (minus the autofocus) (brackets for you Timmbuts) right out of the gate to work on many lenses not just a dedicated one at a small price? Seriously get a bit of perspective. If he was asking $3,000 I could see some balking at price but not the achievement and massive technical skill to pull this off and get it to market without being a big brand name company. Have a few Fosters and if I come to Koalaland you can kick my ass in rugby or cricket and the first round of beer on me. Pushing extremes you will certainly find a few flaws especially in a PROTOTYPE not released to the market yet.

So if the adapter was used on a traditional slr APS sized sensor - would the AF performance improve?I have both a 5DMKII and a 60D. At times, I only want to bring one camera and that could often be the 60D especially if I want more reach from my 70-200 2.8. But if I could get 25.6mm at the wide end of my 24-70 2.8 (and at f2.0) that would be pretty cool!

I wonder if they even could make a pure Canon FF to Canon APS adapter. Perhaps this is an impossibility because they can only work with mirrorless cameras??

True, but saying the maximum aperture "decreased" from 1.4 to 1.0 would have been equally, if not more, confusing. (Technically you are completely correct - the F-number is a number and is supposed to follow the regular numeric comparison.) That's why, in photographic parlance, we say "faster" and "slower". Unfortunately they are no longer well-known terminologies they once were in the good old days. In my humble opinion if we use the word "F-stop" instead we can say "increase" when the F-number decreases numerically, but not sure if you would agree or not.

cyberstudio: They didn't say "aperture increased from 1.4 to 1.0", which would have been be fine. But saying that the F-NUMBER increased from 1.4 to 1.0 is incorrect. The number 1.4 cannot increase to 1.0.

Nevertheless, this preview was a very interesting read, even though as a FF camera owner I'm not in the market. Personally I'm happy that crop camera owners, particularly people interested in video and films, can get a part of the FF IQ experience.

Correct. Unbelievable that someone who takes the effort to criticize an article on a site like DPreview would not know this simple fact. And that it would take 3 replies before someone gave a straight answer...

You could use EV values for all the camera settings, like aperture, and ISO, not sure it would work as well with shutter speed. In fact I wish the camera makers had gone with sensor gain numbers based on EV values instead of using a ISO value from the film days.

Shooting at ISO 100 or 400 is pretty easy to understand but when you get to ISO 400 to ISO 16,000 having EV values would mean a lot more.

Oversimplification is not a good thing. The problem is caused by writing F1.4 and F1.0, when writing F/1.4 and F/1.0 would be more correct. 1/1 is indeed larger than 1/1.4, so the F-number does increase.

that's only because you are writing it incorrectly. If people would write it correctly the same way it is written on most lenses as 50mm 1:1.4 or f/1.4 or f:1.4 or 50/1.4 then we would not have this confusion.

Since a 50mm aperture (50/1.0) is larger than a 35.7mm aperture (50/1.4) it should be obvious that 50/1.0 is larger than 50/1.4. When writers leave out the / and write f1.4 it is needlessly confusing to the non photographer.

Of course there are the idiots that think that f 1:2 means " f1.2" when f/1.2 is 2/3 larger than f/2 and two and a half times as fast.

Folks, you all have me all more confused than ever. In the wikipedia article for "F-number", the formula is N=f/D, so a lens with f=50mm, D=35.7mm will have N=1.4 (not the reciprocal of it). So wikipedia got it wrong too?I suppose the markings on the aperture ring are indeed F-numbers but the maximum aperture ratio written on the lens like 1:1.4 is called something else. (f ratio?) Correct me if I am wrong.

You would get a 20mm-ish f/2.8-ish equivalent lens. The converter actually creates a 13.5mm-ish f/2.0ish lens with APS-C, which ends up being equivalent to the original 20/2.8 specs on 35mm.

What it does is allow you to have the FL and DOF that the lens was intended to have on 35mm on APS-C. This is useful because there aren't equivalents out there to many lenses including your 20/2.8 (where was the last time you saw a 13.5mm f2 DX lens?)

20mm times 0.7 makes it 14mm and then the x2 crop factor of mFT makes it 28mm. The aperture doesn't diminish so it will actually capture more light than the original lens. Depth of Field (and bokeh) will not change so that will be similar to the original F2.8.

Forgive me for saying this, but the purple fringing, chromatic aberration, is much worse than the text suggests (which uses words like "impressive") and reading "You'd be hard-pressed to find significant difference between the two files in the center of the image"... well I beg to differ! Even at center, one image has black, while the other has CA even at center, because there is no black: everything's purple! At this price point, we have the right to have certain expectations.

You have to also consider the device is a substitute for a full frame camera, and is significantly less than the cost a full frame sensor adds to a camera (About $1000 US). There are of course trade offs. Distortion is the other image quality parameter that should decrease with the adapter. Would be nice to see some distortion shots of full frame with a lens and the same shot with the adapted NEX, besides the test chart, maybe a more distant building or something.

@Viking: that is exactly my point: an APSC camera will set you back a thousand bucks, give or take, and the cheapest FF is what, about $2k for a D600? I'd much rather get the FF. But staying on the apsc topic, I buy used legacy lenses on ebay (have a nice Minolta 50mm f1.4) that cost me $100, and the adapter $20 (no optics, just physical adapter). I'm now on the lookout for a nice ~30mm f1.4 as I own the samsung 30mm f2 but want to do better. Now the $600 question: how many lenses, used, can I buy, for the price of this optical reducer that gives me mediocre image non-quality? I just think it is a rip-off. How long will it be, before the chinese are selling adapters like this, for the same price they sell their 2. and x0.45 adapters? (which is around $50) ...and judging by the image quality of this one, it won't be hard to match.

As I have 2 M3 bodies...and cannot finance a digital FullFrame M so that system is quite interesting for me if they make a Leica M version. That would mean I can use my Leica M Optics on a small APSC mirrorless during the moments I just want to do family and friend snapshots etc or when I need really high iso performance.

That would be awsome to get an almost true 35mm F1.4.....@F1 lens on an APSC body !

>>>EDIT.

After some thinking...I just guess it is not possible to put M lenses on a metabone adapter...because Leica lenses have to be really near from the sensor. I think this kind of kill my idea of using my SMALL M lenses on a SMALL Mirrorless.

Of course you are right - the Speed Booster needs two things other than its unique technology to work. The flange focus space released when the mirror box is discarded (so that it might fit inside that space - sadly also not available for dslr bodies) also the lenses use must produce a larger image circle that the sensor for it to be compressed. Therefore it works for lenses designed for 35mm film and their dslr inspired descendants, but "designed for aps-c" - no. Again this is not going to work on to FF sensors unless Medium Format lenses could get their own version of the adapter.

I am very happy with the Leica R version of the Speed Booster and am looking forward to the Nikon version. As I am used to manual focus lenses poor AF is a non-issue for me.

Vignetting is more severe for my very long Telyts. However for short tele and normal lenses the slight corner degradation of image quality doesn't really bother me for real world pictures. Of course one can easily see the degradation when pixel peeking.

It would be interesting to have as part of this review a look at wide angle lenses, such as 14 to 28 mm. I only have Nikon WA lenses and have to wait for the fitting Speed Booster version.

Someone else has pointed out that those Pentax lenses have levers and things sticking out of the back that are sure to prone to play funny devils with the adapter optics. Maybe Pentax could licence the design to Pentax and they could solve that problem themself?

I'd love someone to test the Canon MP-E 65mm f2.8 on this adapter? Whilst more of a niche thing it could be of interest to users of this lens. One of the limitations of this lens on smaller formats is that the minimum magnification of 1:1 is a bit restrictive. It's generally reckoned to provide a better range of magnification on FF. However, something like a NEX6 with this adapter would still be considerably cheaper than a FF camera. AF is irrelevant as this lens doesn't have it.

i have one of those lenses as well, am working on it. Also I have an older Canon EOS TS-E 24mm f3.5 under test right at the moment. So far it has not recognised the MF magnification mode - perhaps it is because it is one of the few Canon EOS lenses that only has manual focus?

Thanks I'd very much forward to see the results. Being as this lens is a bit different than the others, and the extension might mean it performs differently. Although I have tried the MP-E 65mm with a Sigma 1.4x converter and it performed well. The only thing being the camera didn't recognise was that a converter was attached, but it sill functioned. Apparently it's because the lens wasn't designed to work with converters.

John Hallmen did a nice side by side with the MP-E 65mm on a 5D mkII and a NEX7 and the normal Metabones adaptier. His one disappointment being the smaller crop, the speed booster overcomes overcomes this problem. For a while he asked people to judge the difference in photos he'd taken, and most couldn't tell the difference, and guessed wrong. So there's potential.http://www.flickr.com/photos/johnhallmen/7644589020/

In 5 years this will be even more amazing. This is an adapter and not designed for a single lens so some will work better than others. Imagine using your FF glass on a 6D and a mirror less APS size Sony as a back up with adapter.Let's say you have an expensive Cannon 35 f1.4 and with two adapters the speed booster and the regular one it's like having two lenses say a 35 and about a 50 or a 28 and about a 40. Pretty sweet.